xref: /external/icu/icu4c/source/i18n/unicode/unumsys.h

/*
*****************************************************************************************
* Copyright (C) 2013-2014, International Business Machines
* Corporation and others. All Rights Reserved.
*****************************************************************************************
*/

#ifndef UNUMSYS_H
#define UNUMSYS_H

#include "unicode/utypes.h"

#if !UCONFIG_NO_FORMATTING

#include "unicode/uenum.h"
#include "unicode/localpointer.h"

/**
 * \file
 * \brief C API: UNumberingSystem, information about numbering systems
 *
 * Defines numbering systems. A numbering system describes the scheme by which
 * numbers are to be presented to the end user. In its simplest form, a numbering
 * system describes the set of digit characters that are to be used to display
 * numbers, such as Western digits, Thai digits, Arabic-Indic digits, etc., in a
 * positional numbering system with a specified radix (typically 10).
 * More complicated numbering systems are algorithmic in nature, and require use
 * of an RBNF formatter (rule based number formatter), in order to calculate
 * the characters to be displayed for a given number. Examples of algorithmic
 * numbering systems include Roman numerals, Chinese numerals, and Hebrew numerals.
 * Formatting rules for many commonly used numbering systems are included in
 * the ICU package, based on the numbering system rules defined in CLDR.
 * Alternate numbering systems can be specified to a locale by using the
 * numbers locale keyword.
 */

/**
 * Opaque UNumberingSystem object for use in C programs.
 * @stable ICU 52
 */
struct UNumberingSystem;
typedef struct UNumberingSystem UNumberingSystem;  /**< C typedef for struct UNumberingSystem. @stable ICU 52 */

/**
 * Opens a UNumberingSystem object using the default numbering system for the specified
 * locale.
 * @param locale    The locale for which the default numbering system should be opened.
 * @param status    A pointer to a UErrorCode to receive any errors. For example, this
 *                  may be U_UNSUPPORTED_ERROR for a locale such as "en@numbers=xyz" that
 *                  specifies a numbering system unknown to ICU.
 * @return          A UNumberingSystem for the specified locale, or NULL if an error
 *                  occurred.
 * @stable ICU 52
 */
U_STABLE UNumberingSystem * U_EXPORT2
unumsys_open(const char *locale, UErrorCode *status);

/**
 * Opens a UNumberingSystem object using the name of one of the predefined numbering
 * systems specified by CLDR and known to ICU, such as "latn", "arabext", or "hanidec";
 * the full list is returned by unumsys_openAvailableNames. Note that some of the names
 * listed at http://unicode.org/repos/cldr/tags/latest/common/bcp47/number.xml - e.g.
 * default, native, traditional, finance - do not identify specific numbering systems,
 * but rather key values that may only be used as part of a locale, which in turn
 * defines how they are mapped to a specific numbering system such as "latn" or "hant".
 *
 * @param name      The name of the numbering system for which a UNumberingSystem object
 *                  should be opened.
 * @param status    A pointer to a UErrorCode to receive any errors. For example, this
 *                  may be U_UNSUPPORTED_ERROR for a numbering system such as "xyz" that
 *                  is unknown to ICU.
 * @return          A UNumberingSystem for the specified name, or NULL if an error
 *                  occurred.
 * @stable ICU 52
 */
U_STABLE UNumberingSystem * U_EXPORT2
unumsys_openByName(const char *name, UErrorCode *status);

/**
 * Close a UNumberingSystem object. Once closed it may no longer be used.
 * @param unumsys   The UNumberingSystem object to close.
 * @stable ICU 52
 */
U_STABLE void U_EXPORT2
unumsys_close(UNumberingSystem *unumsys);

#if U_SHOW_CPLUSPLUS_API
U_NAMESPACE_BEGIN

/**
 * \class LocalUNumberingSystemPointer
 * "Smart pointer" class, closes a UNumberingSystem via unumsys_close().
 * For most methods see the LocalPointerBase base class.
 * @see LocalPointerBase
 * @see LocalPointer
 * @stable ICU 52
 */
U_DEFINE_LOCAL_OPEN_POINTER(LocalUNumberingSystemPointer, UNumberingSystem, unumsys_close);

U_NAMESPACE_END
#endif

/**
 * Returns an enumeration over the names of all of the predefined numbering systems known
 * to ICU.
 * @param status    A pointer to a UErrorCode to receive any errors.
 * @return          A pointer to a UEnumeration that must be closed with uenum_close(),
 *                  or NULL if an error occurred.
 * @stable ICU 52
 */
U_STABLE UEnumeration * U_EXPORT2
unumsys_openAvailableNames(UErrorCode *status);

/**
 * Returns the name of the specified UNumberingSystem object (if it is one of the
 * predefined names known to ICU).
 * @param unumsys   The UNumberingSystem whose name is desired.
 * @return          A pointer to the name of the specified UNumberingSystem object, or
 *                  NULL if the name is not one of the ICU predefined names. The pointer
 *                  is only valid for the lifetime of the UNumberingSystem object.
 * @stable ICU 52
 */
U_STABLE const char * U_EXPORT2
unumsys_getName(const UNumberingSystem *unumsys);

/**
 * Returns whether the given UNumberingSystem object is for an algorithmic (not purely
 * positional) system.
 * @param unumsys   The UNumberingSystem whose algorithmic status is desired.
 * @return          TRUE if the specified UNumberingSystem object is for an algorithmic
 *                  system.
 * @stable ICU 52
 */
U_STABLE UBool U_EXPORT2
unumsys_isAlgorithmic(const UNumberingSystem *unumsys);

/**
 * Returns the radix of the specified UNumberingSystem object. Simple positional
 * numbering systems typically have radix 10, but might have a radix of e.g. 16 for
 * hexadecimal. The radix is less well-defined for non-positional algorithmic systems.
 * @param unumsys   The UNumberingSystem whose radix is desired.
 * @return          The radix of the specified UNumberingSystem object.
 * @stable ICU 52
 */
U_STABLE int32_t U_EXPORT2
unumsys_getRadix(const UNumberingSystem *unumsys);

/**
 * Get the description string of the specified UNumberingSystem object. For simple
 * positional systems this is the ordered string of digits (with length matching
 * the radix), e.g. "\u3007\u4E00\u4E8C\u4E09\u56DB\u4E94\u516D\u4E03\u516B\u4E5D"
 * for "hanidec"; it would be "0123456789ABCDEF" for hexadecimal. For
 * algorithmic systems this is the name of the RBNF ruleset used for formatting,
 * e.g. "zh/SpelloutRules/%spellout-cardinal" for "hans" or "%greek-upper" for
 * "grek".
 * @param unumsys   The UNumberingSystem whose description string is desired.
 * @param result    A pointer to a buffer to receive the description string.
 * @param resultLength  The maximum size of result.
 * @param status    A pointer to a UErrorCode to receive any errors.
 * @return          The total buffer size needed; if greater than resultLength, the
 *                  output was truncated.
 * @stable ICU 52
 */
U_STABLE int32_t U_EXPORT2
unumsys_getDescription(const UNumberingSystem *unumsys, UChar *result,
                       int32_t resultLength, UErrorCode *status);

#endif /* #if !UCONFIG_NO_FORMATTING */

#endif